The present invention relates to frame connector structures of the types generally described in U.S. Pat. No. 3,603,628(Smith, et al--Sept. 7, 1971) and in pending U.S. patent application Ser. No. 06/117,252(Zummer-filed Jan. 31, 1980). Such prior art connector structures generally comprise: a rigid body component of inverted U-shaped configuration comprising three planar walls including an apertured horizontal wall and two vertical flanking-walls having co-elevational bottom-edges defining the body component bottomplane; and a spring means attached to the body component and positioned loftily above and parallel to the bottom-plane so as to extend along the apertured wall inner surface, the spring member carrying a locking projection extending upwardly through the horizontal wall aperture. Such prior art connector structures are intended to be closely telescopically received within an end of an elongate tubular frame member comprising interconnected longitudinal panels. The tubular frames are typically of rectangular cross-sectional shape and including: vertical left-panel and right-panel for frictional engagements along the connector body flanking-walls; a horizontal bottom-panel for frictional engagement along the connector body bottom-plane; and an apertured top-panel for frictional engagement along the outer surface of the connector horizontal wall. These four frictional engagements entirely suffice for rigidly maintaining the intended longitudinal directional orientation for the tubular frame member (and without the necessity for the latching assist by the spring means locking projection). However, after some weeks or months of post-installation wear-and-tear, the walls/panels frictional engagements have become diminished to such extent that the spring means latching upwardly through the frame aperture becomes absolutely necessary to rigidly maintain the frame member longitudinal orientation. Prior art workers have proceeded under the assumption that nothing can be done about the progressive diminishment of the walls/panels frictional engagement forces, whereby their efforts have been devoted almost exclusively to increasing the strength and reliability of the spring means at the latchable locking projection.